Question 1

Which of the following statements best explains why the second ionization energy of sodium ($$\mathrm{Na}) is $$much higher than its first ionization energy?

Accepted Answer

The second electron is removed from a completely filled valence shell, which is more stable.

Question 2

Which of the following compounds is most likely to be ionic based on the elements involved?

Accepted Answer

$$\mathrm{NaCl}$$

Question 3

According to Coulomb's Law, which factor most strongly affects the energy of an ionic bond?

Accepted Answer

The magnitude of the charges on the ions and the distance between them.

Question 4

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

$$\mathrm{(NH_4$)_2SO_4}$$

Question 5

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 6

Which of the following best describes why bond formation is an exothermic process?

Accepted Answer

Bond formation releases energy because the system moves to a lower potential energy state.

Question 7

Which molecule below has a polar covalent bond but is overall nonpolar?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 8

What is the formal charge on the central atom in the Lewis structure of $$\mathrm{NO_3$^-} ($$nitrate ion)?

Accepted Answer

0

Question 9

Which of the following best explains why ozone ($$\mathrm{O_3$}) $$can absorb UV-B radiation while $$\mathrm{O_2$}$$ cannot?

Accepted Answer

Ozone has resonance structures that allow electron delocalization, enabling absorption of UV-B.

Question 10

Which of the following molecules has a trigonal planar shape according to VSEPR theory?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 11

Which of the following statements about bond energies and bond lengths is correct?

Accepted Answer

Triple bonds have higher bond energies and shorter bond lengths than single bonds.

Question 12

Given the following bond energies: $$\mathrm{C-H}$$ = $$413\ \mathrm{kJ/mol}$$, $$\mathrm{O-H}$$ = $$463\ \mathrm{kJ/mol}$$, $$\mathrm{O=O}$$ = $$498\ \mathrm{kJ/mol}$$, calculate the approximate enthalpy change ($$\Delta H) $$for the reaction: $$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}.$$

Accepted Answer

$$-802\ \mathrm{kJ/mol}$$

Question 13

Which of the following best describes the concept of constructive interference in chemical bonding?

Accepted Answer

Constructive interference occurs when two atomic orbitals overlap and increase electron density between nuclei, forming a bond.

Question 14

Which hybridization is used by carbon in ethene ($$\mathrm{C_2H_4}$$)?

Accepted Answer

$$\mathrm{sp^2$}$$

Question 15

Which of the following statements about sigma ($$\sigma) $$and pi ($$\pi) $$bonds is correct?

Accepted Answer

A sigma bond is formed by head-on overlap of orbitals, while a pi bond is formed by side-on overlap.

Question 16

Which of the following best explains why $$\mathrm{H_2$} is $$stable but $$\mathrm{He_2$} is $$not, according to molecular orbital theory?

Accepted Answer

$$\mathrm{H_2$}$$ has more electrons in bonding orbitals than antibonding orbitals, while $$\mathrm{He_2$}$$ has equal numbers in both.

Question 17

Which of the following is the correct name for $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 18

Which of the following best describes the role of cis- and trans- isomers in the chemistry of vision?

Accepted Answer

The conversion between cis- and trans- isomers in retinal triggers a signal in the visual process.

Question 19

Which of the following best describes the concept of an energy carrier as discussed in Lecture 20?

Accepted Answer

An energy carrier is a molecule that stores and transfers energy within a system.

Study Guide: Atomic Properties, Chemical Bonding, and Molecular Structure

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